It's a known pattern from the Libochovice glassworks in Czechoslovakia.
The exact piece Rob has isn't shown in the pre-1958 catalogue, but there's a same-shaped piece with an added handle shown as a basket.
Correction after checking:
This piece is Czech, it is pattern number 1832, it should be 240mm diameter. It is shown in the catalogue dated before 1958 for glass made at the Libochovice glassworks (before WW2 this was the Feigl and Morávek glassworks, postwar it became part of the nationalised Sklo Union group of glass factories), so could be made anytime pre- or post-war from 1934 onwards.
Stylewise it is very 1930s art deco, so I doubt it was made any later than the 1960s.
There were other pieces made in the same design, including a really nice flat cake stand with a heart-shaped metal handle, a bon-bon dish with lid, bowls, plates and a couple of other bits.